1. Technical Field
An aspect of the present invention relates to a printing apparatus, specifically to a printing apparatus to print in ink containing solid component, which may be deposited in the ink, and concentration gradient may occur therein.
2. Related Art
Conventionally, an inkjet printer to form an image in white ink, in addition to the other colored inks (e.g., cyan, magenta, yellow, and black), has been suggested. The white ink generally contains oxidized titanium and therefore has specifically higher density of colorant with respect to densities of colorants in the other colored inks. Further, a particle size of the white colorant is larger. Therefore, the colorant in the white ink can be easily deposited inside an ink tube.
Accordingly, the densities of the white ink may vary within the tube, and troubles such as irregular ejection of the ink from an inkjet head, insufficient flow of the ink flow to the inkjet head, or uneven densities of the color in a formed image can be caused due to the uneven distribution of the ink within the tube.
Therefore, an inkjet printer with white ink is generally provided with a mechanism to prevent deposition of the colorant in the white ink. For example, Japanese Patent Provisional Publication No. 2004-009685 discloses an inkjet printer having an ink path, in which ink inside an ink cartridge is circulated so that the ink is stirred and smoothly conveyed.
For another example, Japanese Patent Provisional Publication No. 2003-39690 discloses an ink cartridge for an inkjet printer having an stirrer equipment and a vibrator equipment to periodically stir the ink therein.